The positioning and deployment of implantable medical devices within a target site of a patient are common, often repeated, procedures of contemporary medicine. These devices, which may be implantable stents, chronic rhythm management leads, neuromodulation devices, implants, grafts, defibrillators, filters, and catheters, as well as other devices, may be deployed for short or sustained periods of time and may be used for many medicinal purposes. These can include the reinforcement of recently re-enlarged lumens, the replacement of ruptured vessels, and the treatment of disease, such as vascular disease, through the delivery of therapeutic agent.
Coatings may be applied to the surfaces of implantable medical devices to transport therapeutic agent to a target site and to release it at the target site. In certain systems the therapeutic agent is released immediately upon reaching the target site. This burst release may not be favored in certain circumstances as a large amount of the therapeutic agent may be wasted as it is transported away by bodily fluids before it can be absorbed by the targeted area. Likewise, if large amounts of the therapeutic agent are released immediately upon deployment, less therapeutic agent will remain for sustained release of lower dosages over time.